1. Field of the Invention
The present invention relates to a sound effect imparting apparatus which processes audio signals, representing musical tone signals, so as to impart several kinds of sound effects such as a chorus effect and a reverberation effect to musical tones.
2. Prior Art
Accompanied with a recent development in a technology for the digital signal processing, several kinds of digital signal processors (i.e., DSPs) are manufactured. Some of them can effect several kinds of arithmetic operational processes to digital signals inputted thereto by executing a plurality of control programs. Besides, accompanied with a recent progress in manufacturing processes of semiconductor devices, it becomes easy to obtain DSP-type LSI circuits.
In an advanced electronic musical instrument recently developed, one sound effect imparting circuitry which imparts a single sound effect to the musical tone is configured in form of one block (called as an effecter block). A combination of those effecter blocks (i.e., sound effect imparting apparatus) can be equipped in a DSP-type LSI circuit.
The above-mentioned sound effect imparting apparatus has been disclosed in Japanese Patent Publication No.1-19593, which is filed by the present applicant. According to this apparatus, algorithmic structures corresponding to a digital filter and a reverberation sound forming circuit are configured in one sampling period of digital musical tone data in a time-sharing manner under instructions of control programs to be executed. Then, a modulation effect and a reverberation effect are respectively imparted to the musical tone data in a time-sharing manner. The papers of the above publication describe that different sound effects can be imparted to the same musical tone data in parallel.
The above-mentioned sound effect imparting apparatus can respond to five cases: a first case where the modulation effect is only imparted to the musical tone data; a second case where the reverberation effect is only imparted to the musical tone data; a third case where the reverberation effect is imparted to the musical tone data after imparting the modulation effect; a fourth case where the modulation effect is imparted to the musical tone data after imparting the reverberation effect; and a fifth case where the modulation effect and reverberation effect are respectively imparted to the musical tone data in parallel. The above apparatus, however, can merely perform five kinds of sound-effect imparting operations. In short, the conventional apparatus has a drawback in that the number of the sound effects to be imparted to the musical tone data is restricted.